1. Field of the Invention
The present invention relates to a suspension structure for a wheelchair, and more particularly to a suspension structure comprised of front cantilever, movable arm and sliding assembly, which are provided between front jockey wheel, driving wheel and frame of a wheelchair.
2. Description of the Prior Arts
A conventional wheelchair with suspension structure as shown in FIGS. 1 and 2 (as disclosed by U.S. Pat. No. 6,199,647), wherein between a frame 10, driving wheel 11 and front jockey wheel 12 is provided with plural compression springs 13, the compression springs 13 serve to timely raise or lower down the front jockey wheel 12 and the driving wheel 11 upon encountering a raised ground, or similar barrier of the like, so as to enable the wheelchair to overcome the barrier. However, there are some deficiencies will be found in real operation:
First, the front jockey wheel 12 and the driving wheel 11 are independently structured, and which are adjusted by the compression springs 13 corresponds to road condition, in this case, upon encountering barrier, the body of the wheelchair will substantially tilt and swing sharply (caused by the compression and expansion of the compression springs), it is unsafe for user to sit on an unstable wheelchair. Moreover, the respective compression springs 13 also have elastic fatigue problem.
Second, when faced with a barrier and the front jockey wheel 12 is stopped by resistance (when the front jockey wheel abuts against slopping surface of the barrier), since the suspension structures of the front jockey wheel 12 and that of the driving wheel 11 are not interactively connected, the friction of the driving wheel with the road can not be increased correspondingly, in this case, the wheelchair is not easy to roll over the barrier.
Third, since the compression springs 13 serve as suspension structure for the driving wheel 11 and the front jockey wheel 12, the suspension structure is very complexly designed as comprising at least a pair of front cantilevers 14, a pair of drive rods 15, four pieces of compression spring 13 and shafts 16, a pair of stop rods 17. Thus the cost is pretty high.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional suspension structure for a wheelchair.